Document Details
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Document Type |
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Thesis |
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Document Title |
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PHYSIOLOGICAL ROLE OF JASMONATES IN DEFENSE AGAINST SPODOPTERA EXIGUA HERBIVORY IN TOMATO AND MAIZE PLANTS دور الجاسمونات الوظيفي في مقاومه الاصابه بحشره دوده ورق القطن الصغرى في نباتي الطماطم و الذره |
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Subject |
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Faculty of Sciences |
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Document Language |
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Arabic |
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Abstract |
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Jasmonates proposed to have a prospective key role in the plant insect interaction. However, the early events and the signalling mechanisms of jasmonate have yet to be fully elucidated. To obtain some insights into the early events of plants defence response to Spodoptera exigua infestation, we investigated fresh and dry biomass of tomato and maize shoot, plant pigment, soluble carbohydrates, proteins and amino acids content as an indication for plant resistance. The antioxidative responses followed by determining the concentration of hydrogen peroxide (H2O2), phenols and ascorbic acid (AA) in addition to the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT). Jasmonic acid (JA), methyl jasmonate (MeJA) and jasmonyl-L-isoleucine (JA-L-Ile) were quantified using HPLC-MS/MS. All data were collected after 2 hours, 2 days and 1 week following the infestation.
The results indicated that, shoot fresh and dry weight of tomato significantly decreased compared with control after 2 day and 1 week of infestation, while maize shoot fresh and dry biomass decreased than the control only after 1 week of infestation. Spodoptera exigua attack did not change Chl a/b ratio in tomato, while maize recorded a greater adaptability at the beginning of the infestation by decreasing Chl a/b ratio. Soluble carbohydrates content did not change in infested tomato leaves compared to control, while increased in infested maize at 2 h and 2 days. Free amino acids content reduced lower than control in tomato leaves at all observed time periods due to S. exigua attack, while in maize higher concentrations of free amino acids accumulated in infested plants after 2 h and 2 days. Taken together, we could conclude that the defence responses in maize were more efficient than that in tomato.
Moreover, the infestation increases H2O2 and AA concentration in maize leaves at 2 hours and 2 days after infestation while no change recorded in tomato leaves compared to their corresponding controls. Free phenols content increased in infested tomato leaves more than control. The infestation enhances SOD, CAT and APX activities in tomato and maize leaves. H2O2 content in the leaves of studied plants correlated with their differential defence responses. Therefore, it could be used as a diffusible signal to activate defensive genes in maize leaves, as recorded by increasing CAT and APX activities.
In both plants, S. exigua infestation induced JA, MeJA and JA-L-Ile to high levels at 2 h then, decreased gradually by increasing infestation time. JA concentration in infested maize was much higher than that in infested tomato leaves. However, MeJA and JA-L-Ile concentration in infested tomato leaves was higher than that in maize. In control plants, JA did not record, while MeJA recorded in comparable values both in tomato and maize. Therefore, JA assumed to play the main role in increasing defence responses to S. exigua. infestation as a direct signalling molecule. However MeJA could play an indirect role by inducing JA accumulation. |
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Supervisor |
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Prof. Sameera Omar Bafeel |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1439 AH
2018 AD |
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Co-Supervisor |
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Dr. Manal Hussein El-Zohri |
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Added Date |
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Thursday, June 7, 2018 |
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Researchers
| وفاء جمعان الزهراني | Al-Zahrani, Wafaa Jamaan | Researcher | Master | |
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